Plant growth promoting potential of Bacillus spp. isolated from rhizosphere of cocoa (Theobroma cacao L.)
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Date
2010-08
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Abstract
A total of 185 bacilli were isolated from rhizosphere soils of cocoa from various locations in southern states of India and they were subsequently screened in vitro for plant growth promoting (PGP) traits such as production of IAA, ACC deaminase, HCN, siderophore, chitinases and antibiotics, ammonification, ability to grow on N-free media and solubilization of phosphates. It was found that 91 % of the Bacillus spp. isolates produced ammonia; less than 20 % isolates produced HCN and siderophore; IAA production was noticed in 22 % isolates and 19 % isolates were found to produce antibiotics. About 49 % of 185 Bacillus isolates solubilized phosphates; 50 % of isolates could grow on N-free medium and 71 % of isolates showed ACC deaminase production. The isolates could exhibit upto six PGP traits, which may promote plant growth directly or indirectly or synergistically. Thirty six isolates were selected based on the in vitro plant growth promotion potential and were further screened for plant growth promotion under Environmental Plant Growth Chamber (EPGC) conditions. Thirty isolates which showed increase in seedling length in EPGC study were further screened for in vivo growth promotion in cowpea seedlings under greenhouse conditions. Out of 30 isolates tested, 11 were found to increase seedling length and fresh and dry weight of cowpea seedlings when compared to the uninoculated control. The results of this study points to the potential of rhizospheric soil bacilli for plant growth promotion. Further studies are necessary to confirm their effectiveness and potential in the field.
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Keywords
Bacillus spp., plant growth promoting (PGP) traits, Theobroma cacao
Citation
Journal of Plantation Crops, 2010, 38 (2): 97-104